A study in the journal "Infection Control & Hospital Epidemiology" has found that stethoscopes may contain a wide variety of bacteria, including the source of staph infections.

Researchers used DNA sequencing to assess the bacterial content of 50 stethoscopes in an intensive care unit: 20 reusable ones, carried by medical personnel, and 30 single-patient disposable ones, 10 of which were unused.

All 40 of the in-use instruments showed significant traces of bacteria, including microbes linked to common healthcare-associated infections. But researchers could not say if the instruments had made anyone sick, or even if the microbes were alive.

The study showed that cleaning methods approved by the Centers for Disease Control and Prevention were far more effective than the alcohol swabs, hydrogen peroxide wipes or bleach wipes preferred by doctors.